1. Field of the Invention
This invention relates to a method of recording an image on a photosensitive recording medium by scanning the recording medium with a light beam and more particularly relates to an image scanning and recording method in which the conditions for processing the scanned image comprises certain partial changing image gradation, sharpness or the like.
2. Description of the Prior Art
It is common to record an image on a photosensitive recording medium by scanning the recording medium in two directions with an intensity-modulated light beam and an electric scanned image signal may be obtained by reading out the respective stored image. Using this image scanning and recording method, it is possible to electrically process the image signal in various ways, such as changing the signals, gradation, sharpness, magnification or halftone mode prior to recording.
For example, for the case where the contrast of the original image is low, an image exhibiting a high contrast can be obtained therefrom by using a gradation-process wherein the electric image signal obtained by reading out the stored image is adjusted so as to increase the image contrast. It is also possible to obtain a special image effect by decreasing the sharpness of the image. For example, when the original scanned image is a radiation image for use in medical diagnosis it is possible to facilitate observation of the source of a disease from the radiation image by cutting off the high spatial frequency components of the radiation image and reproducing only the low spatial frequency component of the radiation image (namely by lowering the image sharpness). Further, it is also possible to obtain an image suitable for viewing and diagnosising purposes by appropriately changing the magnification or selecting a given dot or line halftone mode.
In the conventional above-mentioned image processing techniques, a predetermined processing of gradation, sharpness, magnification, halftone mode or the like is conducted over the whole original image so as to obtain a processed image in a predetermined manner over the entire area thereof.
However, it is sometimes desired to conduct different processings for different sections of the original image. For example, in the case of a medical X-ray photograph carrying an image of a certain portion of a patient's body, it is sometimes effective to increase the gradation at a predetermined section of the original image and obtain a low-gradation, soft finish, at the remaining section thereof for the purpose of facilitating observation of the source of a desease and for improving the diagnostic efficiency and accuracy thereof. Also, it is sometimes effective for viewing and diagnosis purposes to raise the image sharpness at a given section of the original image and to lower it at the remaining section thereof.
Using the conventional recording method mentioned above, the same processing is applied over the whole area of the original image and, therefore, it is not possible to obtain an image which is partially processed to different degrees at different part, thereof.